The present invention relates to a method for controlling a cruise control. In particular, the invention will find its application in connection with automotive vehicles. The invention also relates to a device intended for such method for controlling a cruise control.
The present invention also relates to a computer program, computer program product and a storage medium for a computer, all to be used with a computer for executing said method.
A cruise control in a vehicle helps the driver to hold a set vehicle speed without the driver having to press an accelerator pedal. A control unit can be arranged to regulate propulsive power, from for example an engine and/or an electric motor, in order to hold said set speed. In alternative known solutions a control unit can be arranged to regulate both propulsive power and braking power of a vehicle. Thus, for example also auxiliary brakes and/or service brakes can be regulated by said control unit in order to maintain a set speed.
If such a vehicle is further equipped with an automatic transmission a transmission control unit will handle gear selection and gear shifting.
GB2319635 discloses a motor vehicle drive force controller, comprising navigation device with a GPS (Global Positioning System) antenna. A drive force characteristic can be throttle gain of an electronic throttle, the gear shift pattern of an automatic transmission, or the air/fuel ratio. A control system automatically controls engine parameters of the vehicle and gear selection in dependence of prevailing road condition obtained from said navigation device.
US20050055157 discloses a navigation system having means for determining a route with optimized fuel consumption. Said navigation system can determine a starting point and an end point of a possible travelling route of said vehicle and based on a desired travelling time a fuel consumption can be calculated and a cruise controller can be controlled in order to arrive at said end point within said desired travelling time.
Even though known solutions can be fairly optimized with regards to fuel consumption there is always an urge towards an even lower fuel consumption.
It is desirable to further reduce fuel consumption when a cruise control is activated in a vehicle.
The method according to an aspect of the invention is a method for controlling a vehicle cruise control in a vehicle comprising (including, but is not necessarily limited to) the steps of:                registering a starting point and an end destination for a possible traveling route of said vehicle;        registering a desired traveling time for said traveling route;        calculating and setting limits for parameters of said cruise control in order to arrive at said end destination on said desired traveling time with as low fuel consumption as possible;        Recalculating said limits as soon as an unexpected occurrence happens when traveling between said starting point and said end destination, and which occurrence affects vehicle average speed;        and in connection to said step of calculating and setting said limits and based on said desired traveling time, selecting a gear shifting pattern which is estimated to give lowest fuel consumption.        
In one embodiment according to an aspect of the invention said limits for said parameters are one or several of:                a maximum vehicle acceleration limit;        a maximum vehicle retardation limit;        a maximum under speed in relation to a vehicle set speed;        a maximum over speed in relation to a vehicle set speed;        a maximum available engine torque;        regulatory limits for the cruise control;        a set speed;        limit for when to engage/disengage a free wheeling function.        
In a further embodiment according to an aspect of the invention said limits are recalculated as soon as an unexpected occurrence happens when traveling between said starting point and said end destination, and which occurrence affects vehicle average speed.
In another embodiment according to an aspect of the invention and in connection to said step of calculating and setting said limits and based on said desired traveling time, said method is characterized in that selecting a gear shifting pattern which is estimated to give lowest fuel consumption.
In an embodiment according to an aspect of the invention, said method is further characterized in that selecting a new gear shifting pattern, which is estimated to give lowest fuel consumption, as soon as an unexpected occurrence happens when traveling between said starting point and said end destination, and which occurrence affects vehicle average speed.
In an embodiment according to an aspect of the invention, said method is further characterized in that in connection to said step of calculating and setting said limits and based on said desired traveling time, selecting between two or several possible routes a traveling route between said starting point and said end destination, which route is estimated to give lowest fuel consumption.
In a further embodiment according to the invention, said method is further characterized in that reevaluating said route selection as soon as an unexpected occurrence happens, which affects vehicle average speed, and basing said reevaluation on a current vehicle position as a starting point.
In an embodiment according to an aspect of the invention said method is further, characterized in that before said step of registering a desired traveling time, estimating and suggesting a first traveling time based on said starting point, said end destination and a vehicle average speed during said traveling route.
In an embodiment according to an aspect of the invention said method is further characterized in that during traveling between said starting point and said end destination continuously recalculating said limits with updated vehicle condition information.
According to another aspect of the invention, a device is provided defined as a vehicle cruise control that comprises (includes, but is not necessarily limited to) a control unit for controlling vehicle speed of a vehicle, a route identifying device and a cruise control driver interface. Said vehicle cruise control is characterized in that said control unit is arranged to perform all the steps of a method according to an aspect of the invention.